It is well known in the art of excavators to provide a coupler between an end of an excavator arm of the excavator and an accessory for that excavator, such as digging buckets for that excavator. Couplers are generally mounted to the arm of the excavator with coupler pins. Then, for coupling a bucket thereto, at the bottom of the coupler, a fixed pair of hooks and either a pair pivoting latching hooks or sliding latching hooks is provided. The hooks engage bucket (or accessory) pins, which are generally provided at the top of the bucket (accessory).
The pivoting or sliding latching hooks are moveable to allow the coupler to both secure and release an accessory to and from the arm of the excavator mechanically, e.g. at the control of a button, using hydraulics or a screw-drive. Generally, however, the hook will be hydraulically actuateable from within the cab of the excavator for remotely securing and releasing the accessory.
It has become increasingly common to provide a safety pin for engaging behind the movable latching hooks (when they are in their latched position), by passing it through the side plates of the coupler, to prevent the hooks from moving backwards, i.e. away from the latched position, in the event of a hydraulic failure. Indeed, this safety feature has become mandatory in some countries. However, because the safety pin has to be inserted manually, in practice it is found that many excavator operators either forget to use it or simply refuse to use it. This presents a significant health and safety risk both to the operator and to those around the excavator.